Re: [PATCH for-6.1 0/1] machine: Disallow specifying topology parameters as zero

[Cornelia Huck]

On Thu, Jul 22 2021, Yanan Wang <wangyanan55@huawei.com> wrote:

> In the SMP configuration, we should either specify a topology
> parameter with a reasonable value (equal to or greater than 1)
> or just leave it omitted and QEMU will calculate its value.
> Configurations which explicitly specify the topology parameters
> as zero like "sockets=0" are meaningless, so disallow them.
>
> However; the commit 1e63fe685804d
> (machine: pass QAPI struct to mc->smp_parse) has documented that
> '0' has the same semantics as omitting a parameter in the qapi
> comment for SMPConfiguration. So this patch fixes the doc and
> also adds the corresponding sanity check in the smp parsers.

Are we expecting any real users to have used that 'parameter=0'
behaviour? I expect that libvirt and other management software already
did the right thing; unfortunately, sometimes weird configuration lines
tend to persist in search results.

>
> This patch originly comes form [1], and it was suggested that
> this patch fixing the doc should be sent for 6.1 to avoid a
> deprecation process in the future.
>
> [1] YPWsThPiZa3mF+zp@redhat.com/">https://lore.kernel.org/qemu-devel/YPWsThPiZa3mF+zp@redhat.com/
>
> Yanan Wang (1):
>   machine: Disallow specifying topology parameters as zero
>
>  hw/core/machine.c | 30 ++++++++++++++++++++++--------
>  hw/i386/pc.c      | 33 ++++++++++++++++++++++++---------
>  qapi/machine.json |  6 +++---
>  3 files changed; 49 insertions(+); 20 deletions(-)